The only taskbar tweaking app i know, with which you can specify the width of the taskbar labels, is Windhawk (freeware).
The module you would have to use for it is "Taskbar Labels for Windows 11", set the "Taskbar item width".
That's how I did it when playing for test with Windhawk. I did not stay using that app, because it takes about 600-700 MByte space on the system partition, only for tweaking the taskbar (it can do some more, but I don't need it for that). I use StartAllBack, but that app has a fixed width of the taskbar labels.
I'm looking at one right now that is about 25 characters wide.
That would not be a correct measure, because 25 characters 'i' are much smaller than 25 characters 'W'!
You would always have to specify width in pixels. So I did:
Taskbar item width: 136
Minimum taskbar item width: 136
Maximum taskbar item width: 136
You might have a look into this thread about Windhawk Mods:
I'm making this thread so that we can accumulate all Windhawk mods in one location. I will continue to update this as I add more. I have been playing with this program a lot more recently and it has very nice editing capabilities. You can run it in portable or installed instance(s). This program...
www.elevenforum.com
There you will find all kinds of links to Windhawk and manuals about it.